﻿/*******************************************************************************
 * Copyright (c) 2007
 * Sergey Berezin, Dmitry Voitsekhovskiy
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms,
 * with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * - Neither the name of the Moscow State University nor the names
 * of its contributors may be used to endorse or promote products
 * derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 ******************************************************************************/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Faml.Operations
{
    public class MatrixOperations
    {
        public delegate double Kernel(Array2d<double> a);

        public static Array2d<double> Conv(Array2d<double> a, Kernel kernel)
        {
            return BaseOperations.Unfold<double>(
                BaseOperations.GetLength<double>(a, 0) - 2,
                BaseOperations.GetLength<double>(a, 1) - 2,
                (i, j) => kernel(BaseOperations.Subarray<double>(a, new int[] { i, i + 1, i + 2 },
                                                                    new int[] {j, j + 1, j + 2})));
        }

        public static Array2d<double> Mul(Array2d<double> a, Array2d<double> b)            
        {
            Array2d<double> m = BaseOperations.Unfold<double>(
                BaseOperations.GetLength<double>(a, 0),
                BaseOperations.GetLength<double>(b, 1),
                (i, j) => BaseOperations.Fold<double>(
                                (u, v) => u + v,
                                BaseOperations.Apply<double>((x) => x[0] * x[1],
                                    BaseOperations.Subarray<double>(a, i, Operations.GetIndices<double>(a, 1)),
                                    BaseOperations.Subarray<double>(b, Operations.GetIndices<double>(b, 0), j)
                                    )
                    )
                );

            return m;
        }

        public static Array2d<int> MulInt(Array2d<int> a, Array2d<int> b)
        {
            Array2d<int> m = BaseOperations.Unfold<int>(
                BaseOperations.GetLength<int>(a, 0),
                BaseOperations.GetLength<int>(b, 1),
                (i, j) => BaseOperations.Fold(
                                (u, v) => u + v,
                                BaseOperations.Apply<int>((x) => x[0] * x[1],
                                    BaseOperations.Subarray<int>(a, i, Operations.GetIndices<int>(a, 1)),
                                    BaseOperations.Subarray<int>(b, Operations.GetIndices<int>(b, 0), j)
                                    )
                    )
                );

            return m;
        }
    }
}
